blame: add support for --[no-]progress option

blame: add support for --[no-]progress option

Teach the command to show progress output when it takes long time to
produce the first line of output; this option cannot be used with
"--incremental" or "--porcelain" options.

git-annotate inherits the option as well.

Helped-by: Eric Sunshine <sunshine@sunshineco.com>
Signed-off-by: Edmundo Carmona Antoranz <eantoranz@gmail.com>
Reviewed-by: Eric Sunshine <sunshine@sunshineco.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>